The 6 commands for facial movement: “Raise your eyebrows.” “Frown.” “Squeeze your eyes closed, tight as you can.” “Puff out your cheeks.” “Grimace.” “Smile” (end on a happy note). Demonstrate for the patient as you go, so they’re not the only one who looks silly.
One side of the face is normal, the other weak, & that’s Bell’s Palsy. Is there anything more to say?
Actually, all that droops isn’t “Bell’s.” It’s more properly a “7th Cranial Nerve (CN7) Palsy,” since “Bell’s” is merely the idiopathic variety. There are other diseases, some serious (like stroke), which also cause a CN7 palsy and need to be ruled-out.
True, these other things are real rare. The overwhelmingly vast majority of facial weakness we encounter will be Bell’s (or Lyme Disease). But that’s the purpose of this blog — sorting quickly and efficiently through the less common / frankly rare possibilities to confirm our confidence in whatever treatment we then opt for, for idiopathic Bell’s.
Also actually, Bell’s Palsy is no longer “idiopathic.” Most cases are caused by reactivation of latent Herpes simplex virus Type-1, acquired in childhood, which migrates around nerve pathways from its home in the trigeminal ganglion. Another significant minority are due to Varicella-Zoster reactivation (shingles, a.k.a. Ramsey-Hunt Syndrome when it affects CN7 or 8). These are what we treat for nowadays.
So what else causes a CN7 Palsy? See our handy Differential:
|Main Rule-Outs||Rare Conditions (“Zebras”)|
Only the left column is worth thinking about. So, starting from the bottom of the right: forget about TB meningitis. It’s just here for completeness; patients are sick and confused, facial palsy is the least of their problems.
Also ignore the very rare Melkersson-Rosenthal Syndrome until there are recurrent palsies, with non-pitting facial edema & fissured tongue. Then send to Neurology, or to Derm for a biopsy.
Facial palsy commonly occurs with Neuro-Sarcoidosis, but neuro-sarcoid itself is rare. Don’t worry about this either, unless the palsy recurs, never resolves, or hasn’t diminished a single bit by 3 months. You can then try a Chest x-ray for hilar adenopathy, but diagnosis is tough, because only 25% of persons may have systemic manifestations of sarcoid.
Even though idiopathic Bell’s Palsy can recur (especially in pregnancy), send unusual palsies to Neuro:
- No improvement at all (not the least tiny bit) by 3 months
- Persistent disability at 1 yr. (Neuro can’t do much, but ought to weigh in)
- If you see vesicles in the canal, or around the external ear, it’s Zoster (a main cause of “idiopathic” Bell’s)
So now we’re left with our 3 main rule-outs before announcing “Bell’s”:
- Stroke / CNS lesions
- Primary HIV
- Lyme Disease
Stroke — It would be quite unusual for stroke to present with an isolated CN7 Palsy, nothing else. There would likely be other basilar artery symptoms like diplopia, dysarthria, dysphagia, hoarseness; deficits in EOMs or CN 9, 10, or 12; limb weakness or ataxia.
Still, to reassure yourself, look for the different manifestations in CN7 weakness that come with a stroke, compared to Bell’s:
- Sparing of the forehead muscles of CN7
- Dissociation between voluntary & spontaneous facial movement
Forehead muscles are enervated by both cerebral hemispheres. So if it’s a stroke that causes the facial weakness, the other side of the brain will maintain forehead strength. The lower eyelid, cheek, nasolabial fold, and mouth will droop, but eyebrow and forehead will be spared.
Tell the patient “Raise your eyebrows, as much as you can.” Then count forehead wrinkles on both sides. If bilaterally equal wrinkles, then worry about a stroke. If the affected side is even slightly less, the deficit is peripheral.
In other words, if the forehead is weak it’s not a stroke. If the forehead is unaffected, both eyebrows rise equally while lower 2/3 of face droops on one side, get an MRI.
Some uncommon strokes prevent a patient from voluntarily moving their face, but automatic and spontaneous movement is preserved. Ask the patient to, “Smile,” and nothing happens. Tell a funny joke, and they smile automatically. So here your clinical skills might depend on your comedic ones [if you’re no stand-up comic, you’ll have to observe well during the visit].
Primary (Acute) HIV — Another “Do Not Miss.”
Up to 80% of persons experience a brief symptomatic period from 1 to 4 weeks after becoming infected with HIV. The vast majority have a mononucleosis-like syndrome, with fever, lymphadenopathy, sore throat, arthralgias, and/or rash. But a minority get neurologic symptoms.
A minority of that minority may present with CN7 palsy. It may occur simultaneously with headache and fever, or occur a few weeks later [ask about a recent syndrome suggestive of viral meningitis]. A bilateral palsy should definitely alert us to something more than simple “Bell’s,” though even unilateral paresis might warrant investigation in the person with significant risk factors for recent HIV acquisition.
Diagnosis of Primary HIV depends on the viral load (HIV RNA testing by PCR). This is the “Window Period;” most simple antibody tests will not have sero-converted yet. Certainly, do not order this on everyone with a Facial Palsy. Do so primarily if:
- Also fever & headache (maybe having occurred 2-3 wks prior)
- Bilateral CN7 deficit
- Significant risk-factors for recent HIV infection
Though Primary HIV is a rare cause of CN7 Palsy, and there’s plenty of time to Dx & Tx established HIV, up to 50% of all HIV transmission may occur during the initial 4 months of infection! So I always take a brief sexual & needle-sharing history with CN7 Palsy.
Lyme Disease — In areas endemic for Lyme Disease, a diagnosis of idiopathic “Bell’s Palsy” should raise eyebrows [bad pun]. That’s because a CN7 Palsy, especially if bilateral, is a common manifestation of the “Early Disseminated” stage, beginning weeks to months after initial infection. One study found 25% of facial palsies during tick season were due to Lyme Disease.
The entire discussion below refers to exposure in an endemic area during nymphal tick season. This includes the northern tip VA, onward to MD, DL, NJ, PA, eastern NY, and New England; also WI, MN
- Also suburbs of Boston, NYC, Phila.
- Parts of Europe; rarely elsewhere in US
- Nymphal tick season: mid-May to late-July
- Sx of Early Disseminated Lyme: June to Dec.
Disclosure: I’ve never worked there. As such, I’m reluctant to write anything. But the intricacies & subtleties of Lyme Diagnosis fascinate me, I’ve read a lot, & it would be rude to write about Bell’s Palsy but exclude an important part of the country. Recommendations below are based on Infectious Disease Society of America (IDSA) guidelines. If I’m off-base, please let me know.
The big problem is that “Early Disseminated Lyme” may require a month of IV antibiotics, so the diagnosis shouldn’t be made lightly. Fortunately, the IgM fraction of antibody to Borrelia burgdorferi (by Western Blot) is usually very high at this stage. But there may be early false-negatives (“window period” before sero-conversion). So for the 75% of people with isolated facial palsy and a negative IgM, follow closely & repeat the test if other symptoms develop (see below).
Isolated facial palsy can be treated with oral antibiotics. Probably also OK if there’s conjunctivitis, arthralgias, or Erythema Migrans lesions left over from Early Lyme (see our summary on Lyme Disease, with pix). Otherwise:* Severe headache / stiff neck require an LP. If normal, oral Tx is OK. * Other “Early Disseminated” symptoms require IV Tx:
- peripheral neuropathy
- other cranial nerve deficits
- cerebellar ataxia (rare)
- peri- / myocarditis (usually mild)
Also, get an EKG. Carditis can be asymptomatic. A long 1° block (>300 msec = 7½ little boxes), or 2° or 3° block, gain admission with telemetry plus IV Tx.
Children & Pregnant Women — diagnose any CN7 palsy in children empirically as Lyme, in case of false-negative antibodies, since idiopathic Bell’s is so rare in Peds. Use the same criteria as above regarding IV vs. p.o. treatment. But another problem: the only oral antibiotic recommended for Early Disseminated Lyme is doxycycline, notoriously contraindicated in children <8 y.o. and in pregnancy. What to do?
The IDSA does in fact allow for single courses in pediatrics. Interestingly, there may be no evidence that Doxy even stains teeth! Since 1997, the American Academy of Pediatrics has OK’d it for rickettsial disease; so why not for Lyme? Read a fascinating brief review of the literature, or absence thereof, about tetracyclines & their purported toxicity (see article in MMWR March 31, 2006 / 55(RR04), esp. under “Treatment & Management, pp. 12-13). Of course, rickettsia are rapidly fatal; Lyme isn’t. But 60 years of tetracycline contraindication is so ingrained in us that nobody wants to risk suggesting that it be used in pregnancy, lactation, or kids <8.
And just for fun, another confounder: B. burgdorferi IgM antibody sometimes persists a long time. The IgG fraction, of course, remains positive forever. And reinfection is certainly possible. As such, the only true gold standard for Lyme Disease is presence of Erythema Migrans rash.
TO SUMMARIZE CN7 PALSY
A patient presents with unilateral facial palsy.
1. Ask a few questions to gain rapport & define chronology, establishing that it never happened before. Determine there’s no significant encephalopathy with confusion (R/O CNS infections).
2. Examine CN7, paying special attention to loss of forehead wrinkles on affected side (R/O stroke). [reminder: in stroke, forehead muscles are preserved, function normally]
3. Briefly examine the other Cranial Nerves.
4. Check the ear for Otitis Media, canal masses. Percuss the mastoid for tenderness.5. If febrile + headache (or if had fever with headache 2-3 wks prior), strongly consider Primary HIV. Check for tender lymph nodes, esp. posterior cervical, sub-occipital, axillary (suggesting Primary HIV).
- Inquire about risks for HIV acquisition in last 30 days
- If decide to W/U, order HIV antibody and Viral Load
- Seek an EM rash (or compatible Hx), arthralgias, conjunctivitis. Examine entire skin (within reason)
- If severe headache / stiff neck: consider LP [admit if positive]
- Obtain an EKG (admit to CCU if heart block)
- Other Sx of Early Disseminated Lyme require admission for IV Tx: radiculopathy, peripheral neuropathy, cerebellar ataxia, other cranial nerve deficits, & peri-/myocarditis
- Children: Dx Lyme empirically, since Bell’s is so rare in Peds.
- While awaiting antibody results for adults, Tx for Bell’s [see below]
7. None of above findings? Now call it Bell’s Palsy (for simplicity’s sake, even though it’s likely due to Herpes simplex or zoster).
TREATMENT of idiopathic Bell’s Palsy (even though this Blog is about Diagnosis, a few brief words about what I do in my own practice):1. Reassure it’s not a stroke (patient’s overriding fear)
- Explain it’s due to HSV-1, acquired as child (NOT the STD Herpes)
- 85% began to recover within 3 wks
- 71% recovered fully, 13% had slight residua, 16% significant sequelae
- Only 60% of those with complete paralysis regained normal function
- Works best if begun within a few days of onset, not at all after a week
- Almost all studies found no benefit adding anti-virals to prednisone in mild cases
- If severe, tape it in daytime too
- Place doubled eye patch gently onto socket, then affix tape to forehead & cheek
- Don’t tape lid directly; it’ll detach & scratch cornea
- Explain to patient the goal is to keep lid closed, not to keep light out.
6. If patient anxious & dubious, schedule follow-up (to reassure)7. Send to Neuro if:
- recurrent CN7 Palsy
- bilateral palsy that isn’t Lyme or Primary HIV
- other cranial nerve deficits
- no improvement at all within 3 months
- persistent disability at 1 year
- Don’t treat for Lyme until serology is back. There’s plenty of time to prevent Late Lyme.
- Do give Prednisone as above. Because if it’s not Lyme, you’ll have lost the opportunity for steroids to help if you don’t start them within 3-4 days.
One final word — Factitious Bell’s Palsy
With the physiologic “Bell’s Reflex,” the eyeball turns upward whenever we squeeze our eye shut. This is protective (a surgeon once told me he’d seen [dead] patients with 100% total-body-area burns, but the eyeballs were spared).
So when you tell a patient with a true CN7 Palsy to, “Squeeze your eyes closed,” and then you pry open the weak lid, you only see sclera (eyeball turned up).
If you ever see the pupil staring at you, you know there was incomplete effort. Maybe they’re malingering, maybe have a conversion reaction, maybe just aren’t trying hard. But it’s not a true palsy.
True CN7 Palsy Factitious CN7 Palsy
And that’s it for CN7. Next time, CN8.